This patch adds the --copy-devices option, which will try to copy
the data inside a device instead of duplicating the device node.

To use this patch, run these commands for a successful build:

    patch -p1 <patches/copy-devices.diff
    ./prepare-source
    ./configure                      (optional if already run)
    make

based-on: 1ddcdaf3f6808ba53aef9e19f630a18808de22ac
diff --git a/generator.c b/generator.c
--- a/generator.c
+++ b/generator.c
@@ -39,6 +39,7 @@ extern int preserve_acls;
 extern int preserve_xattrs;
 extern int preserve_links;
 extern int preserve_devices;
+extern int copy_devices;
 extern int preserve_specials;
 extern int preserve_hard_links;
 extern int preserve_executability;
@@ -1750,7 +1751,7 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		goto cleanup;
 	}
 
-	if (!S_ISREG(file->mode)) {
+	if (!(S_ISREG(file->mode) || (copy_devices && IS_DEVICE(file->mode)))) {
 		if (solo_file)
 			fname = f_name(file, NULL);
 		rprintf(FINFO, "skipping non-regular file \"%s\"\n", fname);
diff --git a/options.c b/options.c
--- a/options.c
+++ b/options.c
@@ -48,6 +48,7 @@ int append_mode = 0;
 int keep_dirlinks = 0;
 int copy_dirlinks = 0;
 int copy_links = 0;
+int copy_devices = 0;
 int preserve_links = 0;
 int preserve_hard_links = 0;
 int preserve_acls = 0;
@@ -348,6 +349,7 @@ void usage(enum logcode F)
   rprintf(F," -o, --owner                 preserve owner (super-user only)\n");
   rprintf(F," -g, --group                 preserve group\n");
   rprintf(F,"     --devices               preserve device files (super-user only)\n");
+  rprintf(F,"     --copy-devices          copy device contents as regular file\n");
   rprintf(F,"     --specials              preserve special files\n");
   rprintf(F," -D                          same as --devices --specials\n");
   rprintf(F," -t, --times                 preserve modification times\n");
@@ -506,6 +508,7 @@ static struct poptOption long_options[] = {
   {"no-D",             0,  POPT_ARG_NONE,   0, OPT_NO_D, 0, 0 },
   {"devices",          0,  POPT_ARG_VAL,    &preserve_devices, 1, 0, 0 },
   {"no-devices",       0,  POPT_ARG_VAL,    &preserve_devices, 0, 0, 0 },
+  {"copy-devices",     0,  POPT_ARG_NONE,   &copy_devices, 0, 0, 0 },
   {"specials",         0,  POPT_ARG_VAL,    &preserve_specials, 1, 0, 0 },
   {"no-specials",      0,  POPT_ARG_VAL,    &preserve_specials, 0, 0, 0 },
   {"links",           'l', POPT_ARG_VAL,    &preserve_links, 1, 0, 0 },
@@ -2074,6 +2077,9 @@ void server_options(char **args, int *argc_p)
 	else if (remove_source_files)
 		args[ac++] = "--remove-sent-files";
 
+	if (copy_devices)
+		args[ac++] = "--copy-devices";
+
 	if (ac > MAX_SERVER_ARGS) { /* Not possible... */
 		rprintf(FERROR, "argc overflow in server_options().\n");
 		exit_cleanup(RERR_MALLOC);
diff --git a/rsync.c b/rsync.c
--- a/rsync.c
+++ b/rsync.c
@@ -34,6 +34,7 @@ extern int preserve_xattrs;
 extern int preserve_perms;
 extern int preserve_executability;
 extern int preserve_times;
+extern int copy_devices;
 extern int am_root;
 extern int am_server;
 extern int am_sender;
@@ -326,7 +327,8 @@ int read_ndx_and_attrs(int f_in, int *iflag_ptr, uchar *type_ptr,
 
 	if (iflags & ITEM_TRANSFER) {
 		int i = ndx - cur_flist->ndx_start;
-		if (i < 0 || !S_ISREG(cur_flist->files[i]->mode)) {
+		struct file_struct *file = cur_flist->files[i];
+		if (i < 0 || !(S_ISREG(file->mode) || (copy_devices && IS_DEVICE(file->mode)))) {
 			rprintf(FERROR,
 				"received request to transfer non-regular file: %d [%s]\n",
 				ndx, who_am_i());
diff --git a/sender.c b/sender.c
--- a/sender.c
+++ b/sender.c
@@ -309,6 +309,20 @@ void send_files(int f_in, int f_out)
 			exit_cleanup(RERR_PROTOCOL);
 		}
 
+		/* On Linux systems (at least), st_size is typically 0 for devices.
+		 * If so, try to determine the actual device size. */
+		if (IS_DEVICE(st.st_mode) && st.st_size == 0) {
+			OFF_T off = lseek(fd, 0, SEEK_END);
+			if (off == (OFF_T) -1)
+				rsyserr(FERROR, errno, "failed to seek to end of %s to determine size", fname);
+			else {
+				st.st_size = off;
+				off = lseek(fd, 0, SEEK_SET);
+				if (off != 0)
+					rsyserr(FERROR, errno, "failed to seek back to beginning of %s to read it", fname);
+			}
+		}
+
 		if (st.st_size) {
 			int32 read_size = MAX(s->blength * 3, MAX_MAP_SIZE);
 			mbuf = map_file(fd, st.st_size, read_size, s->blength);
